System and method for producing a sugar stream with front end oil separation

ABSTRACT

An improved dry grind system and method for producing a sugar stream from grains or similar carbohydrate sources and/or residues, such as for biochemical production, with front end oil separation. Prior to or after saccharification, oil can be removed from a sugar/carbohydrate stream. After saccharification and prior to a sugar conversion process, the sugar/carbohydrate stream includes a desired Dextrose Equivalent (DE) where DE describes the degree of conversion of starch to dextrose can be produced, with such sugar stream being available for biochemical production, e.g., alcohol production, or other processes. In addition, the systems and methods also can involve the removal of certain grain components, e.g., corn kernel components, including protein and/or fiber. In other words, oil separation and sugar stream production occurs on the front end of the system and method.

TECHNICAL FIELD

The present invention relates generally to systems and methods for usein the biochemical (e.g., biofuel), food, feed, nutrition, enzymes,amino acids, proteins, and/or pharmacy industries and, morespecifically, to improved dry grind systems and methods for producing asugar stream, such as for biochemical production.

BACKGROUND

The conventional processes for producing various types of biochemicals,such as biofuels (e.g., alcohol) and other chemicals, from grainsgenerally follow similar procedures. Wet mill processing plants convert,for example, corn grain, into several different co-products, such asgerm (for oil extraction), gluten feed (high fiber animal feed), glutenmeal (high protein animal feed) and starch-based products such asalcohol (e.g., ethanol or butanol), high fructose corn syrup, or foodand industrial starch. Dry grind plants generally convert grains, suchas corn, into two products, namely alcohol (e.g., ethanol or butanol)and distiller's grains with solubles. If sold as wet animal feed,distiller's wet grains with solubles are referred to as DWGS. If driedfor animal feed, distiller's dried grains with solubles are referred toas DDGS. This co-product provides a secondary revenue stream thatoffsets a portion of the overall alcohol production cost.

With respect to the wet mill process, FIG. 1 is a flow diagram of atypical wet mill alcohol (e.g., ethanol) production process 10. Theprocess 10 begins with a steeping step 12 in which grain (e.g., corn) issoaked for 24 to 48 hours in a solution of water and sulfur dioxide inorder to soften the kernels for grinding, leach soluble components intothe steep water and loosen the protein matrix with the endosperm. Cornkernels contain mainly starch, fiber, protein and oil. The mixture ofsteeped corn and water is then fed to a degermination mill step (firstgrinding) 14 in which the corn is ground in a manner that tears open thekernels and releases the germ so as to make a heavy density (8.5 to 9.5Be) slurry of the ground components, primarily a starch slurry. This isfollowed by a germ separation step 16 that occurs by flotation and useof a hydrocyclone(s) to separate the germ from the rest of the slurry.The germ is the part of the kernel that contains the oil found in corn.The separated germ stream, which contains some portion of the starch,protein and fiber, goes to germ washing to remove starch and protein,and then to a dryer to produce about 2.7 to 3.2 pounds (dry basis) ofgerm per bushel of corn (lb/bu). The dry germ has about 50% oil contenton a dry basis.

The remaining slurry, which is now devoid of germ but contains fiber,gluten (i.e., protein), and starch, is then subjected to a fine grindingstep (second grinding) 20 in which there is total disruption ofendosperm and release of endosperm components, namely gluten and starch,from the fiber. This is followed by a fiber separation step 22 in whichthe slurry is passed through a series of screens in order to separatethe fiber from starch and gluten and to wash the fiber clean of glutenand starch. The fiber separation stage 22 typically employs staticpressure screens or rotating paddles mounted in a cylindrical screen(i.e., paddle screens). Even after washing, the fiber from a typical wetgrind mill contains 15 to 20% starch. This starch is sold with the fiberas animal feed. The remaining slurry, which is now generally devoid offiber, is subjected to a gluten separation step 24 in whichcentrifugation or hydrocyclones separate starch from the gluten. Thegluten stream goes to a vacuum filter and dryer to produce gluten(protein) meal.

The resulting purified starch co-product then can undergo a jet cookingstep 26 to start the process of converting the starch to sugar. Jetcooking refers to a cooking process performed at elevated temperaturesand pressures, although the specific temperatures and pressures can varywidely. Typically, jet cooking occurs at a temperature of about 93 to110° C. (about 200 to 230° F.) and a pressure of about 30 to 50 psi.This is followed by liquefaction 28, saccharification 30, fermentation32, yeast recycling 34, and distillation/dehydration 36 for a typicalwet mill biochemical system. Liquefaction occurs as the mixture or“mash” is held at 90 to 95° C. in order for alpha-amylase to hydrolyzethe gelatinized starch into maltodextrins and oligosaccharides (chainsof glucose sugar molecules) to produce a liquefied mash or slurry. Inthe saccharification step 30, the liquefied mash is cooled to about 50°C. and a commercial enzyme known as gluco-amylase is added. Thegluco-amylase hydrolyzes the maltodextrins and short-chainedoligosaccharides into single glucose sugar molecules to produce aliquefied mash. In the fermentation step 32, a common strain of yeast(Saccharomyces cerevisae) is added to metabolize the glucose sugars intoethanol and CO₂.

Upon completion, the fermentation mash (“beer”) will contain about 15%to 18% ethanol (volume/volume basis), plus soluble and insoluble solidsfrom all the remaining grain components. The solids and some liquidremaining after fermentation go to an evaporation stage where yeast canbe recovered as a byproduct. Yeast can optionally be recycled in a yeastrecycling step 34. In some instances, the CO₂ is recovered and sold as acommodity product. Subsequent to the fermentation step 32 is thedistillation and dehydration step 36 in which the beer is pumped intodistillation columns where it is boiled to vaporize the ethanol. Theethanol vapor is separated from the water/slurry solution in thedistillation columns and alcohol vapor (in this instance, ethanol) exitsthe top of the distillation columns at about 95% purity (190 proof). The190 proof ethanol then goes through a molecular sieve dehydrationcolumn, which removes the remaining residual water from the ethanol, toyield a final product of essentially 100% ethanol (199.5 proof). Thisanhydrous ethanol is now ready to be used for motor fuel purposes.Further processing within the distillation system can yield food gradeor industrial grade alcohol.

No centrifugation step is necessary at the end of the wet mill ethanolproduction process 10 as the germ, fiber, and gluten have already beenremoved in the previous separation steps 16, 22, 24. The “stillage”produced after distillation and dehydration 36 in the wet mill process10 is often referred to as “whole stillage” although it also istechnically not the same type of whole stillage produced with atraditional dry grind process described in FIG. 2 below, since noinsoluble solids are present. Other wet mill producers may refer to thistype of stillage as “thin” stillage.

The wet grind process 10 can produce a high quality starch product forconversion to alcohol, as well as separate streams of germ, fiber, andprotein, which can be sold as co-products to generate additional revenuestreams. However, the overall yields for various co-products can be lessthan desirable and the wet grind process is complicated and costly,requiring high capital investment as well as high-energy costs foroperation.

Because the capital cost of wet grind mills can be so prohibitive, somealcohol plants prefer to use a simpler dry grind process. FIG. 2 is aflow diagram of a typical dry grind alcohol (e.g., ethanol) productionprocess 100. As a general reference point, the dry grind method 100 canbe divided into a front end and a back end. The part of the method 100that occurs prior to distillation 110 is considered the “front end,” andthe part of the method 100 that occurs after distillation 110 isconsidered the “back end.” To that end, the front end of the dry grindprocess 100 begins with a grinding step 102 in which dried whole cornkernels can be passed through hammer mills for grinding into meal or afine powder. The screen openings in the hammer mills or similar devicestypically are of a size 6/64 to 9/64 inch, or about 2.38 mm to 3.57 mm,but some plants can operate at less than or greater than these screensizes. The resulting particle distribution yields a very wide spread,bell type curve, which includes particle sizes as small as 45 micronsand as large as 2 mm to 3 mm. The majority of the particles are in therange of 500 to 1200 microns, which is the “peak” of the bell curve.

After the grinding step 102, the ground meal is mixed with cook water tocreate a slurry at slurry step 103 and a commercial enzyme calledalpha-amylase is typically added (not shown). The slurry step 103 isfollowed by a liquefaction step 104 whereat the pH is adjusted to about5.2 to 5.8 and the temperature maintained between about 50° C. to 105°C. so as to convert the insoluble starch in the slurry to solublestarch. Various typical liquefaction processes, which occur at thisliquefaction step 104, are discussed in more detail further below. Thestream after the liquefaction step 104 has about 30% dry solids (DS)content, but can range from about 29-36%, with all the componentscontained in the corn kernels, including starch/sugars, protein, fiber,starch, germ, grit, oil, and salts, for example. Higher solids areachievable, but this requires extensive alpha amylase enzyme to rapidlybreakdown the viscosity in the initial liquefaction step. Theregenerally are several types of solids in the liquefaction stream: fiber,germ, and grit.

Liquefaction may be followed by separate saccharification andfermentation steps, 106 and 108, respectively, although in mostcommercial dry grind ethanol processes, saccharification andfermentation can occur simultaneously. This single step is referred toin the industry as “Simultaneous Saccharification and Fermentation”(SSF). Both saccharification and SSF can take as long as about 50 to 60hours. Fermentation converts the sugar to alcohol. Yeast can optionallybe recycled in a yeast recycling step (not shown) either during thefermentation process or at the very end of the fermentation process.Subsequent to the fermentation step 108 is the distillation (anddehydration) step 110, which utilizes a still to recover the alcohol.

Finally, a centrifugation step 112 involves centrifuging the residualsproduced with the distillation and dehydration step 110, i.e., “wholestillage” in order to separate the insoluble solids (“wet cake”) fromthe liquid (“thin stillage”). The liquid from the centrifuge containsabout 5% to 12% DS. The “wet cake” includes fiber, of which theregenerally are three types: (1) pericarp, with average particle sizestypically about 1 mm to 3 mm; (2) tricap, with average particle sizesabout 500 micron; (3) and fine fiber, with average particle sizes ofabout 250 microns. There may also be proteins with a particle size ofabout 45 microns to about 300 microns.

The thin stillage typically enters evaporators in an evaporation step114 in order to boil or flash away moisture, leaving a thick syrup whichcontains the soluble (dissolved) solids (mainly protein andstarches/sugars) from the fermentation (25 to 40% dry solids) along withresidual oil and fine fiber. The concentrated slurry can be sent to acentrifuge to separate the oil from the syrup in an oil recovery step116. The oil can be sold as a separate high value product. The oil yieldis normally about 0.6 lb/bu of corn with high free fatty acids content.This oil yield recovers only about ⅓ of the oil in the corn, with partof the oil passing with the syrup stream and the remainder being lostwith the fiber/wet cake stream. About one-half of the oil inside thecorn kernel remains inside the germ after the distillation step 110,which cannot be separated in the typical dry grind process usingcentrifuges. The free fatty acids content, which is created when the oilis heated and exposed to oxygen throughout the front and back-endprocess, reduces the value of the oil. The (de-oil) centrifuge onlyremoves less than 50% because the protein and oil make an emulsion,which cannot be satisfactorily separated.

The syrup, which has more than 10% oil, can be mixed with thecentrifuged wet cake, and the mixture may be sold to beef and dairyfeedlots as Distillers Wet Grain with Solubles (DWGS). Alternatively,the wet cake and concentrated syrup mixture may be dried in a dryingstep 118 and sold as Distillers Dried Grain with Solubles (DDGS) todairy and beef feedlots. This DDGS has all the corn and yeast proteinand about 67% of the oil in the starting corn material. But the value ofDDGS is low due to the high percentage of fiber, and in some cases theoil is a hindrance to animal digestion and lactating cow milk quality.

Further, with respect to the liquefaction step 104, FIG. 3 is a flowdiagram of various typical liquefaction processes that define theliquefaction step 104 in the dry grind process 100. Again, the dry grindprocess 100 begins with a grinding step 102 in which dried whole cornkernels are passed through hammer mills or similar milling systems suchas roller mills, flaking mills, impacted mill, or pin mills for grindinginto meal or a fine powder. The grinding step 102 is followed by theliquefaction step 104, which itself includes multiple steps as isdiscussed next.

Each of the various liquefaction processes generally begins with theground grain or similar material being mixed with cook and/or backsetwater, which can be sent from evaporation step 114 (FIG. 2 ), to createa slurry at slurry tank 130 whereat a commercial enzyme calledalpha-amylase is typically added (not shown). The pH is adjusted here,as is known in the art, to about 5.2 to 5.8 and the temperaturemaintained between about 50° C. to 105° C. so as to allow for the enzymeactivity to begin converting the insoluble starch in the slurry tosoluble liquid starch. Other pH ranges, such as from pH 3.5 to 7.0, maybe utilized, and an acid treatment system using sulfuric acid, forexample, can be used as well for pH control and conversion of thestarches to sugars.

After the slurry tank 130, there are normally three optional pre-holdingtank steps, identified in FIG. 3 as systems A, B, and C, which may beselected depending generally upon the desired temperature and holdingtime of the slurry. With system A, the slurry from the slurry tank 130is subjected to a jet cooking step 132 whereat the slurry is fed to ajet cooker, heated to about 120° C., held in a U-tube or similar holdingvessel for about 2 min to about 30 min, then forwarded to a flash tank.In the flash tank, the injected steam flashes out of the liquid stream,creating another particle size reduction and providing a means forrecovering the injected stream. The jet cooker creates a sheering forcethat ruptures the starch granules to aid the enzyme in reacting with thestarch inside the granule and allows for rapid hydration of the starchgranules. It is noted here that system A may be replaced with a wetgrind system. With system B, the slurry is subjected to a secondaryslurry tank step 134 whereat the slurry is maintained at a temperaturefrom about 90° C. to 100° C. for about 10 min to about 1 hour. Withsystem C, the slurry from the slurry tank 130 is subjected to asecondary slurry tank—no steam step 136, whereat the slurry from theslurry tank 130 is sent to a secondary slurry tank, without any steaminjection, and maintained at a temperature of about 80° C. to 90° C. forabout 1 to 2 hours. Thereafter, the slurry from each of systems A, B,and C is forwarded, in series, to first and second holding tanks 140 and142 for a total holding time of about 60 minutes to about 4 hours attemperatures of about 80° C. to 90° C. to complete the liquefaction step104, which then is followed by the saccharification and fermentationsteps 106 and 108, along with the remainder of the process 100 of FIG. 2. While two holding tanks are shown here, it should be understood thatone holding tank, more than two holding tanks, or no holding tanks maybe utilized.

In today's typical grain to biochemical plants (e.g., corn to alcoholplants), many systems, particularly dry grind systems, process theentire corn kernel through fermentation and distillation. Such designsrequire about 30% more front-end system capacity because there is onlyabout 70% starch in corn, with less for other grains and/or biomassmaterials. Additionally, extensive capital and operational costs arenecessary to process the remaining non-fermentable components within theprocess. By removing undesirable, unfermentable components prior tofermentation (or other reaction process), more biochemical, biofuel, andother processes become economically desirable.

Further, attempts have been made in the dry grinding industry todesirably recover high value by-products, such as oil. However, attemptsto separate oil from the “hammer milled” slurry have failed because ofthe high concentration of solids and because the oil is not releasedfrom the solid particles. Some success has been realized with processesrecovering oil from the evaporation stages of the dry mill process.However, the yield is relatively low, and the oil must move through theentire process, including fermentation, prior to evaporation. Thepresence of the oil in these steps of the process can be detrimental tothe efficiency of the remaining parts of the process. Attempts have beenmade to recover the oil directly after fermentation. However, theprocess of mixing and fermentation emulsifies the oil, and this makes itvery difficult to remove. Other attempts have been made to recover oildirectly from corn by solvent extraction but the cost, for example, istoo high for commercial use.

It thus would be beneficial to provide an improved dry milling systemand method that produces a sugar stream, such as for biochemicalproduction, that may be similar to the sugar stream produced byconventional wet corn milling systems, but at a fraction of the cost andgenerate additional revenue from high value by-products, such as oil,protein, and/or fiber, for example, with desirable yield.

SUMMARY OF THE INVENTION

The present invention provides for a dry milling system and method thatproduces a sugar stream, such as for biochemical production, with frontend oil separation that may be similar to the sugar stream produced byconventional wet corn milling systems, but at a fraction of the cost,and generate additional revenue from high value by-products, such asoil, protein and/or fiber, for example, with desirable yield.

In one embodiment, a method for producing a sugar stream with front endoil separation is provided and includes mixing ground grain particleswith a liquid to produce a slurry including starch and free oil; andsubjecting the slurry to liquefaction to provide a liquefied starchsolution including the free oil followed by separating the free oil fromthe liquefied starch solution prior to saccharification of the starch toyield an oil by product. Thereafter, the method further includessubjecting at least a portion of the liquefied starch solution tosaccharification to convert the starch to simple sugars and produce asaccharified stream including the simple sugars. After saccharificationbut prior to further processing of the simple sugars, the method furtherincludes separating the saccharified stream into a first solids portionand a first liquid portion including the simple sugars, wherein thefirst liquid portion defines a sugar stream having a dextrose equivalentof at least 20 DE and a total unfermentable solids fraction that is lessthan or equal to 30% of a total solids content.

In another embodiment, a system for producing a sugar stream with frontend oil separation is provided and includes a slurry tank in whichground grain particles mix with a liquid to produce a slurry includingstarch and free oil; a liquefaction system that receives the slurry andprovides a liquefied starch solution including the free oil, and whereatthe starch begins to convert to oligosaccharides; and an oil separationdevice that is situated after the liquefaction system and separates thefree oil from the liquefied starch solution to yield an oil by-product.The system further includes a saccharification system that is situatedafter the oil separation device and that receives at least a portion ofthe liquefied starch solution after the free oil is separated, thesaccharification system converts the oligosaccharides to simple sugarsthereby producing a saccharified stream including the simple sugars. Thesystem also includes a first separation device that receives andseparates the saccharified stream into a first solids portion and afirst liquid portion including the simple sugars, wherein the firstliquid portion defines a sugar stream having a dextrose equivalent of atleast 20 DE and a total unfermentable solids fraction that is less thanor equal to 30% of the total solids content, the first separation devicesituated prior to any sugar conversion device that receives andprocesses the simple sugars to produce a biochemical.

In another embodiment, a method for producing a sugar stream with frontend oil separation is provided and includes mixing ground grainparticles with a liquid to produce a slurry including starch and freeoil; and subjecting the slurry to liquefaction to provide a liquefiedstarch solution including the starch and the free oil. The methodfurther includes subjecting at least a portion of the liquefied starchsolution to saccharification to convert the starch to simple sugars andproduce a saccharified stream including the simple sugars and the freeoil and, separating the free oil from the saccharified stream to yieldan oil by product. Thereafter and prior to further processing of thesimple sugars, the method includes separating the remaining saccharifiedstream into a first solids portion and a first liquid portion includingthe simple sugars, wherein the first liquid portion defines a sugarstream having a dextrose equivalent of at least 20 DE and a totalunfermentable solids fraction that is less than or equal to 30% of atotal solids content.

In another embodiment, a system for producing a sugar stream with frontend oil separation is provided and includes a slurry tank in whichground grain particles mix with a liquid to produce a slurry includingstarch and free oil; a liquefaction system that receives the slurry andprovides a liquefied starch solution including the free oil, and whereatthe starch begins to convert to oligosaccharides; and a saccharificationsystem that is situated after the liquefaction system and that receivesat least a portion of the liquefied starch solution, thesaccharification system converts the oligosaccharides to simple sugarsthereby producing a saccharified stream including the simple sugars andthe free oil. The system further includes an oil separation device thatis situated after the saccharification system and separates the free oilfrom the saccharified stream to yield an oil by-product. Thereafter, afirst separation device receives and separates the saccharified streaminto a first solids portion and a first liquid portion including thesimple sugars, wherein the first liquid portion defines a sugar streamhaving a dextrose equivalent of at least 20 DE and a total unfermentablesolids fraction that is less than or equal to 30% of the total solidscontent, the first separation device situated prior to any sugarconversion device that receives and processes the simple sugars toproduce a biochemical.

The features and objectives of the present invention will become morereadily apparent from the following Detailed Description taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,with a detailed description of the embodiments given below, serve toexplain the principles of the invention.

FIG. 1 is a flow diagram of a typical wet mill alcohol productionprocess;

FIG. 2 is a flow diagram of a typical dry grind alcohol productionprocess;

FIG. 3 is a flow diagram of various typical liquefaction processes in atypical dry grind alcohol production process;

FIG. 4 is a flow diagram showing a dry grind system and method forproducing a sugar stream with front end oil separation in accordancewith an embodiment of the invention;

FIG. 5 is a flow diagram showing a dry grind system and method forproducing a sugar stream with front end oil separation in accordancewith another embodiment of the invention; and

FIG. 6 is a flow diagram showing a dry grind system and method forproducing a sugar stream with front end oil separation in accordancewith another embodiment of the invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

FIGS. 1 and 2 have been discussed above and represent flow diagrams of atypical wet mill and dry grind alcohol production process, respectively.FIG. 3 , likewise, has been discussed above and represents varioustypical liquefaction processes in a typical dry grind alcohol productionprocess.

FIGS. 4, 5, and 6 illustrate embodiments of dry grind systems andmethods 200, 300, 400 for producing a sugar stream from grains orsimilar carbohydrate sources and/or residues, such as for biochemicalproduction, with front end oil separation in accordance with the presentinvention. As further discussed in detail below, a sugar/carbohydratestream, which includes a desired Dextrose Equivalent (DE) where DEdescribes the degree of conversion of starch to dextrose (a.k.a.glucose) and/or has had removed therefrom an undesirable amount ofunfermentable components, including in certain embodiments removing freeoil prior to saccharification, can be produced after thesaccharification and prior to fermentation (or other sugarutilization/conversion process), with such sugar stream being availablefor biochemical production, e.g., alcohol production, or otherprocesses. In addition, the present systems and methods 200, 300, 400also involves the removal of certain grain components, e.g., free oilprior to saccharification in certain embodiments and other corn kernelcomponents, including protein and/or fiber, prior to fermentation orother conversion systems, as further discussed below. In other words,sugar stream production and grain component separation, including oilseparation, occurs on the front end of the systems and methods 200, 300,400.

For purposes herein, in one example, the resulting sugar stream that maybe desirable after saccharification, but before fermentation, such asfor use in biochemical production, can be a stream where thestarch/sugars in that stream define at least a 90 DE and/or where thetotal insoluble (unfermentable) solids fraction of the stream is lessthan or equal to 7% of the total solids content in the stream. In otherwords, at least 90% of the total starch/sugar in that stream is dextroseand/or no greater than 7% of the total solids in that stream includesnon-fermentable components. In another example, the sugar stream maydefine at least 95 DE. In another example, the resulting sugar streammay define at least 98 DE. In yet another example, the starch/sugars inthe stream can define at least a 20, 30, 40, 50, 60, 70, or 80 DE. Inanother example, the total insoluble (unfermentable) solids fraction ofthe stream is less than or equal to 3% of the total solids content inthe stream. In another example, the total insoluble (unfermentable)solids fraction of the stream is less than or equal to 1%. In stillanother example, the total insoluble (unfermentable) solids fraction ofthe stream is less than or equal to 10%, 15%, 20%, 25%, or 30%. In otherwords, the total fermentable content (fermentable solids fraction) ofthe stream may be no more than 30%, 40%, 50%, 60%, 70%, 75%, 80%, 85%,90%, 95%, 97%, or 99% of the total solids content in the stream. Inanother example, on a dry mass basis, the weight % fermentable materialin the sugar stream that may be desired is greater than or equal to 80%.In another example, on a dry mass basis, the weight % fermentablematerial in a sugar stream is greater than or equal to 85%, 90%, 95%,98%, or 99%.

In addition, although the systems and methods 200, 300, 400 describedherein will generally focus on corn or kernel components, virtually anytype of grain, whether whole and fractionated or any carbohydratesource, including, but not limited to, wheat, barley, sorghum, rye,rice, oats, sugar cane, tapioca, cassava, pea, or the like, as well asother biomass products, can be used. And broadly speaking, it should beunderstood that the entire grain or biomass or less than the entiregrain, e.g., corn and/or grit and/or endosperm or biomass, may be groundand/or used in the systems and methods 200, 300, 400.

With further reference now to FIG. 4 , in this dry grind system andmethod 200, grains such as corn and/or corn particles, for example, canbe subjected to an optional first grinding step 202, which involves useof a hammer mill, roller mill, pin mill, impact mill, flaking mill, orthe like, either in series or parallel, to grind the corn and/or cornparticles to particle sizes less than about 7/64 inch or, in anotherexample, less than about 10/64 inch and allow for the release of oiltherefrom to define free oil. In one example, the screen size forseparating the particles can range from about 24/64 inch to about 2/64inch. In another example, the resulting particle sizes are from about 50microns to about 3 mm. The grinding also helps break up the bondsbetween the fiber, protein, starch, and germ. In one example, screensize or resulting particle size may have little to no impact on theability to separate the sugar from the remaining kernel or similar rawmaterial component(s). If the carbohydrate source is pre-ground orinitially in particulate form, the optional grind step 202 may beexcluded from the system and method 200.

Next, the ground corn flour is mixed with backset liquid at slurry tank204 to create a slurry. Optionally, fresh water may be added so as tolimit the amount of backset needed here. An enzyme(s), such as alphaamylase, optionally can be added to the slurry tank 204 or in a slurryblender (not shown) between the first grinding step 202 and the slurrytank 204. The slurry may be heated at the slurry tank 204 from about 66°C. (150° F.) to about 93° C. (200° F.) for about 10 min to about 120min. The stream from the slurry tank 204 contains about 0.5 lb/bu freeoil, about 1.5 lb/bu germ (particle size ranges from about 50 microns toabout 3 mm), about 1.8 lb/bu grit (particle size ranges from about 50microns to about 3 mm), which can include starch, and about 4.25 lb/bufiber (particle size ranges from about 50 microns to about 3 mm).

The stream from the slurry tank 204 next may be subjected to an optionalsecond grinding/particle size reduction step 206, which may involve useof a disc mill, hammer mill, a pin or impact mill, a roller mill, agrind mill, or the like, to further grind the corn particles to particlesizes less than about 850 microns and allow for additional release ofoil and protein/starch complexes therefrom. In another example, theparticle sizes are from about 300 microns to about 650 mm. The grindingfurther helps continue to break up the bonds between the fiber, protein,and starch and facilitates the release of free oil from germ particles.The stream from the second grinding/particle size reduction step 206contains about 0.1 lb/bu to about 1.0 lb/bu free oil.

Prior to subjecting the stream from the slurry tank 204 to the optionalsecond grinding/particle size reduction step 206, the slurry may besubjected to an optional liquid/solid separation step 207 to remove adesired amount of liquids therefrom. The liquid/solid separation step207 separates a generally liquefied solution (about 60% to about 80% byvolume), which includes free oil, protein, and fine solids (which do notneed grinding), from heavy solids cake (about 20% to about 40% byvolume), which includes the heavier fiber, grit, and germ, which caninclude bound oil, protein, and/or starch. The liquid/solid separationstep 308 uses dewatering equipment, e.g., a paddle screen, a vibrationscreen, screen decanter centrifuge or conic screen centrifuge, apressure screen, a preconcentrator, a filter press, or the like, toaccomplish separation of the solids from the liquid portion. The finesolids can be no greater than 200 microns. In another example, the finesolids are no greater than 500 microns, which is generally dependentupon the screen size openings used in the liquid/solid separationdevice(s).

In one example, the dewatering equipment is a paddle screen, whichincludes a stationary cylinder screen with a high speed paddle withrake. The number of paddles on the paddle screen can be in the range of1 paddle per 4 to 8 inches of screen diameter. In another example, thedewatering equipment is a preconcentrator, which includes a stationarycylinder screen with a low speed screw conveyor. The conveyor pitch onthe preconcentrator can be about ⅙ to about ½ of the screen diameter.The number of paddles on the paddle screen and the conveyor pitch on thepreconcentrator can be modified depending on the amount of solids in thefeed. The gap between the paddle screen and paddle can range from about0.04 to about 0.2 inch. A smaller gap gives a drier cake with highercapacity and purer fiber but loses more fiber to filtrate. A larger gapgives a wetter cake with lower capacity and purer liquid (less insolublesolid). The paddle speed can range from 400 to 1200 RPM. In anotherexample, the paddle speed can range from 800 to 900 RPM. A higher speedprovides higher capacity but consumes more power. One suitable type ofpaddle screen is the FQ-PS32 paddle screen, which is available fromFluid-Quip, Inc. of Springfield, Ohio.

The screen for the dewatering equipment can include a wedge wire typewith slot opening, or a round hole, thin plate screen. The round holescreen can help prevent long fine fiber from going through the screenbetter than the wedge wire slot opening, but the round hole capacity islower, so more equipment may be required if using round hole screens.The size of the screen openings can range from about 45 microns to about500 microns. In another example, the screen openings can range from 100to 300 microns. In yet another example, the screen openings can rangefrom 200 to 250 microns. Smaller screen openings tend to increase theprotein/oil/alcohol yield with higher equipment and operation cost,whereas larger screen openings tend to lower protein/oil/alcohol yieldwith less equipment and operation cost.

The wet cake or dewatered solids portion of the stream at theliquid/solid separation step 207 (about 60% to about 65% water) next maybe subjected to the optional second grinding/particle size reductionstep 206, as described above. After milling, the solids can be mixedwith the liquefied starch solution from the liquid/solid separation step207, as shown, to form a heavy slurry and subjected to liquefaction step208.

In particular, the liquefaction step 208 can include multiple steps asdiscussed above and shown in FIG. 3 . In one embodiment, the pH can beadjusted here to about 5.2 to about 5.8 and the temperature maintainedbetween about 50° C. to about 105° C. so as to convert the insolublestarch in the slurry to soluble or liquid starch. Other pH ranges, suchas from pH 3.5-7.0, may be utilized and an acid treatment system usingsulfuric acid, for example, may be used as well for pH control and forconversion of the starches to sugars. The slurry may be furthersubjected to jet cooking whereat the slurry is fed to a jet cooker,heated to about 120° C., held for about 2 min to about 30 min, thenforwarded to a flash tank. The jet cooker creates a sheering force thatruptures the starch granules to aid the enzyme in reacting with thestarch inside the granule and for hydrating the starch molecules. Inanother embodiment, the slurry can be subjected to a secondary slurrytank whereat steam is injected directly to the secondary slurry tank andthe slurry is maintained at a temperature from about 80° C. to about100° C. for about 30 min to about one hour. In yet another embodiment,the slurry can be subjected to a secondary slurry tank with no steam. Inparticular, the slurry is sent to a secondary slurry tank without anysteam injection and maintained at a temperature of about 80° C. to about90° C. for 1 to 2 hours. Thereafter, the liquefied slurry may beforwarded to a holding tank for a total holding time of about 1 hour toabout 4 hours at temperatures of about 80° C. to about 90° C. tocomplete the liquefaction step 208. With respect to the liquefactionstep 208, pH, temperature, and/or holding time may be adjusted asdesired.

The slurry stream after the liquefaction step 208 has about 28% to about36% dry solids (DS) content with all the components contained in thecorn kernels, including starches/sugars, protein, fiber, germ, grit,oil, and salts, for example. There generally are three types of solidsin the liquefaction stream: fiber, germ, and grit, which can includestarch and protein, with all three solids having about the same particlesize distribution. The stream from the liquefaction step 208 containsabout 1 lb/bu free oil, about 1.5 lb/bu germ particle (size ranges fromless about 50 microns to about 1 mm), about 4.5 lb/bu protein (sizeranges from about 50 microns to about 1 mm), and about 4.25 lb/bu fiber(particle size ranges from about 50 microns to about 3 mm).

After the liquefaction step 208 (but before any potentialsaccharification, fermentation, or other processing of the sugarstream), so as to provide a more desirable sugar stream, the liquefiedsugar stream can be subjected to a solid/liquid separation step 210followed by an oil/liquefied starch solution separation step 212. Inparticular, the solid/liquid separation step 210, which may be optional,uses any suitable filtration device, e.g., a pre-concentrator, paddlescreen, pressure screen, fiber centrifuge, decanter, and the like, toseparate the liquid from the solid material. The screen openings canrange from about 50 microns to about 500 microns and will be selected todesirably separate the fiber, grit, and germ particles from the liquid,which primarily includes the liquefied starch solution with smallamounts of oil, free protein (mainly gluten), and starch. In oneexample, the screen openings are about 50 microns.

The liquid portion may be subjected to the oil/liquefied starch solutionseparation step 212 whereat the liquid portion is subjected to an oilrecovery device to separate out the oil before sending the liquefiedstarch solution to meet up with the solids portion from the solid/liquidseparation step 210 prior to fermentation, such as at saccharificationstep 214, which is discussed below. The oil/liquefied starch solutionseparation step 212 can use any type of oil separation device, such as amud centrifuge, two or three phase decanter, disc decanter, two or threephase disc centrifuge, flotation tank, dissolved air flotationtank/system, and the like, to separate oil from the sugar stream bytaking advantage of density differences. At oil/liquefied starchsolution separation step 212, the liquefied starch solution is used asheavy media liquid to float the oil, which has a density of about 1.05grams/cc to about 1.15 grams/cc. The oil that is recovered at this stagein the process has a much more desirable quality in terms of color andfree fatty acid content (from about 2% to about 5%) as compared to oilthat is recovered downstream, particularly oil recovered aftersaccharification and fermentation. In particular, the color of thepre-saccharification recovered oil is lighter in color and lower in freefatty acid content. The oil yield can include 0.1 lb/bu or greater. Inone example, the oil yield is from about 0.1 lb/bu to about 0.6 lb/bu,or greater than about 0.6 lb/bu. In another example, the oil yield isfrom about 0.2 to about 1.0 lb/bu, or greater than about 1.0 lb/bu.

The separated solids portion from the solid/liquid separation step 210,along with the liquefied starch solution from the oil/liquefied starchsolution separation step 212, can be sent to the saccharification step214 whereat complex carbohydrate and oligosaccharides are further brokendown into simple sugars, particularly single glucose sugar molecules(i.e., dextrose) to produce a liquefied mash. Optionally, a portion orthe entirety of the separated solids portion from the solid/liquidseparation step 210 and/or the liquefied starch solution from theoil/liquefied starch solution separation step 212 can be sent tofermentation step 220 or another conversion step.

In particular, at the saccharification step 214, the slurry stream maybe subjected to a two-step conversion process. The first part of thecook process, in one example, includes adjusting the pH to about 3.5 toabout 7.0, with the temperature being maintained between about 30° C. toabout 100° C. for 1 to 6 hours to further convert the insoluble starchin the slurry to soluble starch, particularly dextrose. In anotherexample, the pH can be 5.2 to 5.8 or 5.5, for example. In anotherexample, the temperature can be maintained at 80° C. for about 5 hours.Also, an enzyme, such as alpha-amylase may be added here. In oneexample, the amount of alpha-amylase may be from about 0.0035 wt % toabout 0.04 wt % of the slurry stream. In another example, the amount ofalpha-amylase may be from about 0.02 wt % to about 0.1 wt % of the totalstream.

The second part of the cook process, in one example, may includeadjusting the pH to about 3.5 to 5.0, with the temperature beingmaintained between about 30° C. to about 100° C. for about 10 minutes toabout 5 hours so as to further convert the insoluble starch in theslurry to soluble starch, particularly dextrose. In another example, thepH can be 4.5. In another example, the temperature can be maintainedfrom about 54° C. (130° F.) to about 74° C. (165° F.) for about 4 hoursor up to about 60 hours. An enzyme, such as glucoamylase, also may beadded here. In one example, the amount of glucoamylase may be from about0.01 wt % to about 0.2 wt % of the slurry stream. In another example,the amount of glucoamylase may be from about 0.08 to about 0.14 wt % ofthe slurry stream. Other enzymes or similar catalytic conversion agentsmay be added at this step or previous steps that can enhance starchconversion to sugar or yield other benefits, such as fiber or cellulosicsugar release, conversion of proteins to soluble proteins, or therelease of oil from the germ.

A saccharified sugar stream having a density of about 1.05 grams/cc toabout 1.15 grams/cc can result here. At this point, the saccharifiedsugar stream may be no less than about 90 DE. In another example, thesaccharified sugar stream may be no less than 20, 30, 40, 50, 60, 70, or80 DE. In this example, the saccharified sugar stream may not beconsidered desirable or “clean” enough, such as for use in biochemical(e.g., biofuel) production, because the total fermentable content of thestream may be no more than 75% of the total solids content in thestream. In this example, the saccharified sugar stream can have a totalsolids fraction of about 25% to about 40%, such solids including sugar,starch, fiber, protein, germ, oil, and ash, for example. In yet anotherexample, the total fermentable content of the stream is no more than 30,40, 50, 60, or 70% of the total solids content in the stream. Theremaining solids are fiber, protein, oil, and ash, for example. Thestream from the saccharification step 214 contains about 0.1 lb/bu toabout 1.0 lb/bu free oil.

After the saccharification step 214 (but before any potentialfermentation or processing of the sugar stream), so as to provide a moredesirable sugar stream, the saccharified sugar stream can be subjectedto an optional sugar separation step 216. The sugar separation step 216filters a generally liquefied solution (about 60 to about 80% byvolume), which includes sugar, free oil, protein, fine solids, fiber,grit and germ, and which has a total solids fraction of about 30%, witha range of about 20% to about 40%, but higher or low solids fractionscan be produced, but may not be economical here. In particular, thesugar separation step 216 includes a clarifier, 2 or 3 phase separator,filtration centrifuge, drum filter, dissolved air flotation, paddlescreen, pressure screen, or the like to accomplish substantialseparation of the solids portion, primarily fiber, germ, grit, which caninclude protein, from the liquid sugar portion, which primarily includessugar (e.g., dextrose), residual oil, and fine solids. The solidsportion, which has a total solids fraction of about 39% or that is in arange of about 25% to about 50%, may be sent on to the fermentation step220.

At this point, the separated sugar stream may be no less than about 90DE. In another example, the liquefied sugar stream may be no less than20, 30, 40, 50, 60, 70, or 80 DE. In this example, the sugar stream heremay be considered desirable or “clean” enough, such as for use inbiochemical production, because the total insoluble (unfermentable)solids fraction of the stream is less than or equal to 10% of the totalsolids of the stream. In another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to7%. In another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 5%. In another example,the total insoluble (unfermentable) solids fraction of the stream isless than or equal to 3%. In another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to1%. In still another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 10%, 15%, 20%, 25%, or30%. In this example, the stream sent to sugar separation step 216 mayhave a total solids fraction of about 27%, or in a range of about 20% toabout 35%, such solids including sugar, starch, fiber, protein and/orgerm, for example.

After the optional sugar separation step 216, the sugar stream may besubjected to an optional microfiltration (or similar filtration) step218, which can include a rotary vacuum filter, micro-filter, membranefiltration, precoat/diatomaceous earth filter, or the like, to produce amore desirable sugar stream, which may be considered a purified orrefined sugar stream, by further separating out any remaining insolublecomponents, color, ash, minerals, or the like. In one example, thefilter screen size here may be from about 0.1 micron to about 100microns. In another example, the filter screen size may be from about 5microns to about 50 microns. Due to the input of water, the sugar streamcan have a total solids fraction of 20-35%. In this example, the sugarstream here may be considered purified or refined enough because thetotal insoluble (unfermentable) solids fraction of the stream is lessthan 10%. In another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 5%. In another example,the total insoluble (unfermentable) solids fraction of the stream isless than or equal to 3%. In another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to1%. In still another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 10%, 15%, 20%, 25%, or30%.

The microfiltration step 218 may be replaced by, or additionallyinclude, ultrafiltration, carbon column color removal, filter press,flotation, adsorption, and/or demineralization technologies (e.g., ionexchange). Resin refining, which includes a combination of carbonfiltration and demineralization in one step, can also be utilized forrefining the sugars. Additionally, due to a low solids content of thesugar stream here, an optional evaporation step (not shown) may be addedhereafter to further concentrate the total solids fraction.

The sugar stream from the microfiltration step 218 can be sent on to afurther processing step, such as a fermentation step where the sugarsare converted, e.g., via a fermenter, to alcohol, such as ethanol orbutanol or any other fermentation conversion process or similar sugarutilization/conversion process, followed by distillation and/orseparation of the desired component(s) (not shown), which can recoverthe alcohol or byproduct(s)/compound(s) produced, as is known in theart. The sugar stream can allow for recovery of a fermentation agentfrom the fermentation step. The fermentation agent can be recovered bymeans known in the art and can be dried as a separate product or, forexample, can be sent to a protein separation step or otherstreams/steps, in the system and method 200, which can allow for captureof the fermentation agent and/or used for further processing.Fermentation agent (such as yeast or bacteria) recycling can occur byuse of a clean sugar source. Following distillation or desiredseparation step(s), the system and method 200 can include any back endtype process(es), which may be known or unknown in the art to process,for example, the whole stillage. The fermentation step may be part of analcohol production system that receives a sugar stream that is not asdesirable or clean, i.e., “dirtier,” than the sugar stream being sentand subjected to the same fermentation step as the dirty sugar stream.Other options for the sugar stream, aside from fermentation, can includefurther processing or refining of the glucose to fructose or othersimple or even complex carbohydrate, processing into feed, microbe basedfermentation (as opposed to yeast based) and other various chemical,pharmaceutical or nutraceutical processing (such as propanol,isobutanol, citric acid or succinic acid), and the like. Such processingcan occur via a reactor, including, for example, a catalytic or chemicalreactor. In one example, the reactor is a fermenter.

Still referring to FIG. 4 , the solid or heavy components from the sugarseparation step 216 and microfiltration step 218 can be combinedtogether and sent to fermentation step 220. These heavier components orunderflow, can be more concentrated in total solids, at about 28%. Thefermentation step 220 is followed by distillation 222. At thedistillation tower, the fermented solution is separated from thestillage, which includes fiber, protein, and germ particles, to producealcohol. The fiber can be separated from the germ particles and protein(gluten) at a fiber/protein separation step 224 by differences inparticle sizes using a screen device, such as a filtration centrifuge,to remove the fiber therefrom. The screen openings normally will beabout 500 microns to capture amounts of tipcap, pericarp, as well asfine fiber, but can range from about 200 microns to about 1,000 microns.The separated fiber is used to produce a low protein (less than about25%)/low oil (less than about 8%) DDG.

If a lower protein and oil content in the fiber is needed or desired,the fiber may be sent to a holding tank (not shown), for example,whereat the pH of the separated fiber can be adjusted to about 8 toabout 10.5 (or about 8 to about 9.5), such as by the addition ofchemicals, e.g., sodium hydroxide, lime, sodium carbonate, trisodiumphosphate, or the like to help release additional oil from the germ.Also, cell wall breaking enzymes, e.g., protease and the like, and/orchemicals, e.g., sodium sulfite and the like, may be added here to helprelease additional oil from the germ. In one example, the fiber can beheld in the tank for about 1 hour at a temperature of about 140° F. toabout 200° F. (or about 180° F. to about 200° F.). Thereafter, the fibercan be subjected to a grind step to release more oil and protein fromthe fiber. The fiber produced by these additional treatment steps cangive a much lower oil (less than 2%) and lower protein (less than 10%)and can be used for secondary alcohol production.

The centrate from the fiber/protein separation step 224 goes to anevaporator 226 to separate any oil therefrom and to produce syrup, whichcan be mixed with the DDG and dried, as represented by numeral 228, togive the low protein (less than about 25%)/low oil (less than about 8%)DDGS, such as for cows or pigs, particularly dairy cows. The DDGScontains less than about 25% protein, less than about 8% oil, and lessthan about 5% starch.

In addition, an optional centrifugation step (not shown) may be providedto recover the xanthophyll content in the emulsion layer of therecovered oils, both prior to and after saccharification 214, and mixedwith the protein by-product prior to drying to increase the feed value.The overflow from the centrifuge(s) can go back to the oil storage tanks(not shown).

With further reference now to FIG. 5 , in this dry grind system andmethod 300, grains such as corn and/or corn particles, for example, canbe subjected to an optional first grinding step 302, which involves useof a hammer mill, roller mill, pin mill, impact mill, flaking mill, orthe like, either in series or parallel, to grind the corn and/or cornparticles to particle sizes less than about 7/64 inch or, in anotherexample, less than about 10/64 inch and allow for the release of oiltherefrom defining free oil. In one example, the screen size forseparating the particles can range from about 24/64 inch to about 2/64inch. In another example, the resulting particle sizes are from about 50microns to about 3 mm. The grinding also helps break up the bondsbetween the fiber, protein, starch, and germ. In one example, screensize or resulting particle size may have little to no impact on theability to separate the sugar from the remaining kernel or similar rawmaterial component(s). If the carbohydrate source is pre-ground orinitially in particulate form, the optional grind step 302 may beexcluded from the system and method 300.

Next, the ground corn flour is mixed with backset liquid at slurry tank304 to create a slurry. Optionally, fresh water may be added so as tolimit the amount of backset needed here. An enzyme(s), such as alphaamylase, optionally can be added to the slurry tank 304 or in a slurryblender (not shown) between the optional first grinding step 302 and theslurry tank 304. The slurry may be heated at the slurry tank 304 fromabout 66° C. (150° F.) to about 93° C. (200° F.) for about 10 min toabout 120 min. The stream from the slurry tank 304 contains about 0.5lb/bu free oil, about 1.5 lb/bu germ (particle size ranges from about 50microns to about 3 mm), about 1.8 lb/bu grit (particle size ranges fromabout 50 microns to about 3 mm), which can include starch, and about4.25 lb/bu fiber (particle size ranges from about 50 microns to about 3mm).

The stream from the slurry tank 304 next may be subjected to an optionalsecond grinding/particle size reduction step 306, which may involve useof a disc mill, hammer mill, a pin or impact mill, a roller mill, agrind mill, or the like, to further grind the corn particles to particlesizes less than about 850 microns and allow for additional release ofoil and protein/starch complexes therefrom. In another example, theparticle sizes are from about 300 microns to about 650 mm. The grindingfurther helps continue to break up the bonds between the fiber, protein,and starch and facilitates the release of free oil from germ particles.The stream from the second grinding/particle size reduction step 306contains about 0.1 lb/bu to about 1.0 lb/bu free oil.

Prior to subjecting the stream from the slurry tank 304 to the optionalsecond grinding/particle size reduction step 306, the slurry may besubjected to an optional liquid/solid separation step 308 to remove adesired amount of liquids therefrom. The liquid/solid separation step308 separates a generally liquefied solution (about 60% to about 80% byvolume), which includes free oil, protein, and fine solids (which do notneed grinding), from heavy solids cake (about 20% to about 40% byvolume), which includes the heavier fiber, grit, and germ, which caninclude bound oil, protein, and/or starch. The liquid/solid separationstep 308 uses dewatering equipment, e.g., a paddle screen, a vibrationscreen, screen decanter centrifuge or conic screen centrifuge, apressure screen, a preconcentrator, a filter press, or the like, toaccomplish separation of the solids from the liquid portion. The finesolids can be no greater than 200 microns. In another example, the finesolids are no greater than 500 microns, which is generally dependentupon the screen size openings used in the liquid/solid separationdevice(s).

In one example, the dewatering equipment is a paddle screen, whichincludes a stationary cylinder screen with a high speed paddle withrake. The number of paddles on the paddle screen can be in the range of1 paddle per 4 to 8 inches of screen diameter. In another example, thedewatering equipment is a preconcentrator, which includes a stationarycylinder screen with a low speed screw conveyor. The conveyor pitch onthe preconcentrator can be about ⅙ to about ½ of the screen diameter.The number of paddles on the paddle screen and the conveyor pitch on thepreconcentrator can be modified depending on the amount of solids in thefeed. The gap between the paddle screen and paddle can range from about0.04 to about 0.2 inch. A smaller gap gives a drier cake with highercapacity and purer fiber but loses more fiber to filtrate. A larger gapgives a wetter cake with lower capacity and purer liquid (less insolublesolid). The paddle speed can range from 400 to 1200 RPM. In anotherexample, the paddle speed can range from 800 to 900 RPM. A higher speedprovides higher capacity but consumes more power. One suitable type ofpaddle screen is the FQ-PS32 paddle screen, which is available fromFluid-Quip, Inc. of Springfield, Ohio.

The screen for the dewatering equipment can include a wedge wire typewith slot opening, or a round hole, thin plate screen. The round holescreen can help prevent long fine fiber from going through the screenbetter than the wedge wire slot opening, but the round hole capacity islower, so more equipment may be required if using round hole screens.The size of the screen openings can range from about 45 microns to about500 microns. In another example, the screen openings can range from 100to 300 microns. In yet another example, the screen openings can rangefrom 200 to 250 microns. Smaller screen openings tend to increase theprotein/oil/alcohol yield with higher equipment and operation cost,whereas larger screen openings tend to lower protein/oil/alcohol yieldwith less equipment and operation cost.

The wet cake or dewatered solids portion of the stream at theliquid/solid separation step 308 (about 60% to about 65% water) next maybe subjected to the optional second grinding/particle size reductionstep 306, as described above. After milling, the solids can be mixedwith the liquefied starch solution from the liquid/solid separation step308, as shown, to form a heavy slurry then subjected to liquefactionstep 310.

In particular, the liquefaction step 310 itself can include multiplesteps as discussed above and shown in FIG. 3 . In one embodiment, the pHcan be adjusted here to about 5.2 to about 5.8 and the temperaturemaintained between about 50° C. to about 100° C. so as to convert theinsoluble starch in the slurry to soluble or liquid starch. Other pHranges, such as from pH 3.5 to 7.0, may be utilized and an acidtreatment system using sulfuric acid, for example, may be used as wellfor pH control and for conversion of the starches to sugars. The slurrymay be further subjected to jet cooking whereat the slurry is fed to ajet cooker, heated to about 120° C., held for about 2 min to about 30min, then forwarded to a flash tank. The jet cooker creates a sheeringforce that ruptures the starch granules to aid the enzyme in reactingwith the starch inside the granule and for hydrating the starchmolecules. In another embodiment, the slurry can be subjected to asecondary slurry tank whereat steam is injected directly to thesecondary slurry tank and the slurry is maintained at a temperature fromabout 80° C. to about 100° C. for about 30 min to about one hour. In yetanother embodiment, the slurry can be subjected to a secondary slurrytank with no steam. In particular, the slurry is sent to a secondaryslurry tank without any steam injection and maintained at a temperatureof about 80° C. to about 90° C. for 1 to 2 hours. Thereafter, theliquefied slurry may be forwarded to a holding tank for a total holdingtime of about 1 hour to about 4 hours at temperatures of about 80° C. toabout 90° C. to complete the liquefaction step 310. With respect to theliquefaction step 310, pH, temperature, and/or holding time may beadjusted as desired.

The slurry stream after the liquefaction step 310 has about 25% to about36% dry solids (DS) content with all the components contained in thecorn kernels, including starches/sugars, protein, fiber, germ, grit,oil, and salts, for example. There generally are three types of solidsin the liquefaction stream: fiber, germ, and grit, which can includestarch and protein, with all three solids having about the same particlesize distribution. The stream from the liquefaction step 310 containsabout 1 lb/bu free oil, about 1.5 lb/bu germ particle (size ranges fromless about 50 microns to about 1 mm), about 4.5 lb/bu protein (sizeranges from about 50 microns to about 1 mm), and about 4.25 lb/bu fiber(particle size ranges from about 50 microns to about 3 mm).

After the liquefaction step 310 (but before any potentialsaccharification, fermentation, or other processing of the sugarstream), so as to provide a more desirable sugar stream, the liquefiedsugar stream can be subjected to a solid/liquid separation step 312 andan oil/liquefied starch solution separation step 314. In particular, thesolid/liquid separation step 312 uses any suitable filtration device,e.g., a pre-concentrator, paddle screen, pressure screen, fibercentrifuge, decanter, and the like, to separate the liquid from thesolid material. The screen openings can range from about 20 microns toabout 500 microns and will be selected to desirably separate the fiber,grit, and germ particles from the liquid, which primarily includes theliquefied starch solution with small amounts of oil, free protein(mainly gluten), and starch. In one example, the screen openings areabout 20 microns. In another example, the screen openings are about 50microns.

The liquid portion can go to the oil/liquefied starch solutionseparation step 314 whereat the liquid portion can be subjected to anoil separation device to separate out the oil before sending theliquefied starch solution to the saccharification step 316, which isdiscussed below. The oil/liquefied starch solution separation step 314can use any type of oil separation device, such as a mud centrifuge, twoor three phase decanter, disc decanter, two or three phase disccentrifuge, flotation tank, dissolved air flotation tank/system, and thelike, to separate oil from the sugar stream by taking advantage ofdensity differences. With a three-phase device, such as a three phasecentrifuge or decanter, a heavier solids portion optionally can beseparated out at the oil/liquified starch solution step 314 from the oiland liquified starch solution. At oil/liquefied starch solutionseparation step 314, the liquefied starch solution is used as heavymedia liquid to float the oil, which has a density of about 1.05 to 1.15grams/cc. The oil that is recovered at this stage in the process has amuch more desirable quality in terms of color and free fatty acidcontent (from about 2% to about 5%) as compared to oil that is recovereddownstream, particularly oil recovered after saccharification andfermentation. In particular, the color of the pre-saccharificationrecovered oil is lighter in color and lower in free fatty acid content.The oil yield can include 0.2 lb/bu or greater. In one example, the oilyield is from about 0.1 to about 1.0 lb/bu.

The separated solids portion from the solid/liquid separation step 312and a portion of the liquefied starch solution from the oil/liquefiedstarch solution separation step 314 can meet up with the solids from themicrofiltration (or similar filtration) step 318, as described below,and be subjected to a further biochemical conversion processing step320. In an embodiment, about 5% to about 95% of the liquefied starchsolution may be sent to the further processing step 320. When theoil/liquefied starch solution separation step 314 is a three phaseseparation step, the solids portion is also sent to the furtherprocessing step 320. Optionally, a portion of the solids portion fromthe oil/liquefied starch solution separation step 314 may be sent to themicrofiltration step 318. In an embodiment, the further processing step320 is a fermentation step where the sugars are converted, e.g., via afermenter, to alcohol, such as ethanol or butanol or any otherfermentation conversion process or similar sugar utilization/conversionprocess, followed by distillation and/or separation of the desiredcomponent(s) (not shown), which can recover the alcohol orbyproduct(s)/compound(s) produced, as is described above with respect tothe system and method 200. Following distillation or desired separationstep(s), the system and method 300 can include any back end typeprocess(es), which may be known or unknown in the art to process, forexample, the whole stillage. The fermentation step may be part of analcohol production system that receives a sugar stream that is not asdesirable or clean, i.e., “dirtier,” than the sugar stream being sentand subjected to the same fermentation step as the dirty sugar stream.Other options for the solids stream, aside from fermentation, caninclude further processing or refining of the solids into feed, microbebased fermentation (as opposed to yeast based) and other variouschemical, pharmaceutical or nutraceutical processing (such as propanol,isobutanol, citric acid or succinic acid), and the like. Such processingcan occur via a reactor, including, for example, a catalytic or chemicalreactor. In one example, the reactor is a fermenter.

The remainder of the liquefied starch solution from the oil/liquefiedstarch solution separation step 314 next can be sent to thesaccharification step 316 whereat complex carbohydrate andoligosaccharides are further broken down into simple sugars,particularly single glucose sugar molecules (i.e., dextrose) to producea liquefied mash. In particular, at the saccharification step 316, theslurry stream may be subjected to a two-step cook process. The firstpart of the cook process, in one example, includes adjusting the pH toabout 3.5 to about 7.0, with the temperature being maintained betweenabout 30° C. to about 100° C. for 1 to 6 hours to further convert theinsoluble starch in the slurry to soluble starch, particularly dextrose.In another example, the pH can be 5.2 to 5.8 or 5.5, for example. Inanother example, the temperature can be maintained at 80° C. for about 5hours. Also, an enzyme, such as alpha-amylase may be added here. In oneexample, the amount of alpha-amylase may be from about 0.0035 to about0.004 wt % of the slurry stream. In another example, the amount ofalpha-amylase may be from about 0.02 to about 0.1 wt % of the totalstream.

The second part of the cook process, in one example, may includeadjusting the pH to about 3.5 to about 5.0, with the temperature beingmaintained between about 30° C. to about 100° C. for about 10 minutes toabout 5 hours so as to further convert the insoluble starch in theslurry to soluble starch, particularly dextrose. In another example, thepH can be 4.5. In another example, the temperature can be maintainedfrom about 54° C. (130° F.) to about 74° C. (165° F.) for about 4 hoursor up to about 60 hours. An enzyme, such as glucoamylase, also may beadded here. In one example, the amount of glucoamylase may be from about0.01 wt % to about 0.2 wt % of the slurry stream. In another example,the amount of glucoamylase may be from about 0.08 wt % to about 0.14 wt% of the slurry stream. Other enzymes or similar catalytic conversionagents may be added at this step or previous steps that can enhancestarch conversion to sugar or yield other benefits, such as fiber orcellulosic sugar release, conversion of proteins to soluble proteins, orthe release of oil from the germ.

A saccharified sugar stream having a density of about 1.05 grams/cc toabout 1.15 grams/cc can result here. At this point, the saccharifiedsugar stream may be no less than about 90 DE. In another example, thesaccharified sugar stream may be no less than 20, 30, 40, 50, 60, 70, or80 DE. In this example, the saccharified sugar stream may not beconsidered desirable or “clean” enough, such as for use in biochemical(e.g., biofuel) production, because the total fermentable content of thestream may be no more than 75% of the total solids content in thestream. In this example, the saccharified sugar stream can have a totalsolids fraction of about 28% to about 36%, such solids including sugar,starch, fiber, protein, germ, oil, and ash, for example. In yet anotherexample, the total fermentable content of the stream is no more than 30,40, 50, 60, or 70% of the total solids content in the stream. Theremaining solids are fiber, protein, oil, and ash, for example. Thestream from the saccharification step 316 contains about 0.1 to about1.0 lb/bu free oil.

After the saccharification step 316 (but before any potentialfermentation or processing of the sugar stream), so as to provide a moredesirable sugar stream, the saccharified sugar stream is subjected to amicrofiltration step 318, which can include a rotary vacuum filter,micro-filter, membrane filtration, precoat/diatomaceous earth filter, orthe like, to produce a more desirable sugar stream, which may beconsidered a purified or refined sugar stream, by substantial separationof the solids portion, primarily fiber, germ, grit, which can includeprotein, from the liquid sugar portion, which primarily includes sugar(e.g., dextrose), residual oil, and fine solids. In one example, thefilter screen size here may be from about 0.1 micron to about 100microns. In another example, the filter screen size may be from about 5microns to about 50 microns. Due to the input of water, the sugar streammay have a total solids fraction of 20-35%. In this example, the sugarstream here may be considered purified or refined enough because thetotal insoluble (unfermentable) solids fraction of the stream is lessthan 10%. In another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 7%. In another example,the total insoluble (unfermentable) solids fraction of the stream isless than or equal to 5%. In another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to3%. In another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 1%. In still anotherexample, the total insoluble (unfermentable) solids fraction of thestream is less than or equal to 10%, 15%, 20%, 25%, or 30%.

At this point, the separated sugar stream may be no less than about 90DE. In another example, the liquefied sugar stream may be no less than20, 30, 40, 50, 60, 70, or 80 DE. In this example, the sugar stream heremay be considered desirable or “clean” enough, such as for use inbiochemical production, because the total insoluble (unfermentable)solids fraction of the stream is less than or equal to 10% of the totalsolids of the stream. In another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to7%. In another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 5%. In another example,the total insoluble (unfermentable) solids fraction of the stream isless than or equal to 3%. In another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to1%. In still another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 10%, 15%, 20%, 25%, or30%. In this example, the stream sent to microfiltration step 318 mayhave a total solids fraction of about 27%, or in a range of about 20% toabout 35%, such solids including sugar, starch, fiber, protein, and/orgerm, for example.

The microfiltration step 318 may be replaced by, or additionallyinclude, ultrafiltration, carbon column color removal, filter press,flotation, adsorption, and/or demineralization technologies (e.g., ionexchange). Resin refining, which includes a combination of carbonfiltration and demineralization in one step, can also be utilized forrefining the sugars. Additionally, due to a low solids content of thesugar stream here, an optional evaporation step (not shown) may be addedhereafter to further concentrate the total solids fraction.

As described above, the heavy or solids (raffinate) components from themicrofiltration step 318 can be sent to meet up with the separatedsolids portion from the solid/liquid separation step 312 and the portionof the liquefied starch solution (and optional solids portion) from theoil/liquefied starch solution separation step 314 and subjected tobiochemical conversion process step 320. These heavier components, orunderflow, can be more concentrated in total solids at about 28%.

In one example, prior to the biochemical conversion process step 320,the combined streams may be subjected to an optional thirdgrinding/particle size reduction step 322, which may involve use of adisc mill, hammer mill, a pin or impact mill, a roller mill, a grindmill, or the like for further grinding of particles. Prior to subjectingthe combined streams to the optional third grinding/particle sizereduction step 322, the stream may be subjected to an optionalliquid/solid separation step 324 to remove a desired amount of liquidstherefrom. The liquid/solid separation step 324 separates the liquidportion of the combined stream, which can include remaining free oil,protein, and fine solids (which do not need grinding), from remainingheavy solids cake, which includes the heavier fiber, grit, and germ,which can include bound oil, protein, and/or starch. The liquid/solidseparation step 324 uses dewatering equipment, e.g., a paddle screen, avibration screen, screen decanter centrifuge or conic screen centrifuge,a pressure screen, a preconcentrator, a filter press, or the like, toaccomplish separation of the solids from the liquid portion. The finesolids can be no greater than 200 microns. In another example, the finesolids are no greater than 500 microns, which is generally dependentupon the screen size openings used in the liquid/solid separationdevice(s).

In one example, the dewatering equipment is a paddle screen, whichincludes a stationary cylinder screen with a high speed paddle withrake. The number of paddles on the paddle screen can be in the range of1 paddle per 4 to 8 inches of screen diameter. In another example, thedewatering equipment is a preconcentrator, which includes a stationarycylinder screen with a low speed screw conveyor. The conveyor pitch onthe preconcentrator can be about ⅙ to about ½ of the screen diameter.The number of paddles on the paddle screen and the conveyor pitch on thepreconcentrator can be modified depending on the amount of solids in thefeed. The gap between the paddle screen and paddle can range from about0.04 to about 0.2 inch. A smaller gap gives a drier cake with highercapacity and purer fiber but loses more fiber to filtrate. A larger gapgives a wetter cake with lower capacity and purer liquid (less insolublesolid). The paddle speed can range from 400 to 1200 RPM. In anotherexample, the paddle speed can range from 800 to 900 RPM. A higher speedprovides higher capacity but consumes more power. One suitable type ofpaddle screen is the FQ-PS32 paddle screen, which is available fromFluid-Quip, Inc. of Springfield, Ohio.

The screen for the dewatering equipment can include a wedge wire typewith slot opening, or a round hole, thin plate screen. The round holescreen can help prevent long fine fiber from going through the screenbetter than the wedge wire slot opening, but the round hole capacity islower, so more equipment may be required if using round hole screens.The size of the screen openings can range from about 45 microns to about500 microns. In another example, the screen openings can range from 100to 300 microns. In yet another example, the screen openings can rangefrom 200 to 250 microns.

The wet cake or dewatered solids portion of the stream at theliquid/solid separation step 324 next may be subjected to the optionalthird grinding/particle size reduction step 322, as described above.After milling, the solids can be mixed with the liquid from theliquid/solid separation step 324, as shown, to form a solid/liquidstream then subjected to the biochemical conversion process step 320.

Concerning now the sugar stream from the microfiltration step 318, thisstream can be sent on to a further processing step, such as afermentation step where the sugars are converted, e.g., via a fermenter,to alcohol, such as ethanol or butanol or any other fermentationconversion process or similar sugar utilization/conversion process,followed by distillation and/or separation of the desired component(s)(not shown), which can recover the alcohol or byproduct(s)/compound(s)produced, as is known in the art. The sugar stream can allow forrecovery of a fermentation agent from the fermentation step. Thefermentation agent can be recovered by means known in the art and can bedried as a separate product or, for example, can be sent to a proteinseparation step or other streams/steps, in the system and method 300,which can allow for capture of the fermentation agent and/or used forfurther processing. Fermentation agent (such as yeast or bacteria)recycling can occur by use of a clean sugar source. Followingdistillation or desired separation step(s), the system and method 300can include any back end type process(es), which may be known or unknownin the art to process, for example, the whole stillage. The fermentationstep may be part of an alcohol production system that receives a sugarstream that is not as desirable or clean, i.e., “dirtier,” than thesugar stream being sent and subjected to the same fermentation step asthe dirty sugar stream. Other options for the sugar stream, aside fromfermentation, can include further processing or refining of the glucoseto fructose or other simple or even complex carbohydrates, processinginto feed, microbe based fermentation (as opposed to yeast based) andother various chemical, pharmaceutical, enzymatic, amino acid, ornutraceutical processing (such as propanol, isobutanol, citric acid orsuccinic acid), and the like. Such processing can occur via a reactor,including, for example, a catalytic or chemical reactor. In one example,the reactor is a fermenter. It should be noted that those skilled in theart will understand that the microfiltration system can include one ormore units and may be situated in series and/or parallel flow.

With reference now to FIG. 6 , in this dry grind system and method 400,grains such as corn and/or corn particles, for example, can be subjectedto an optional first grinding step 402, which involves use of a hammermill, roller mill, pin mill, impact mill, flaking mill, or the like,either in series or parallel, to grind the corn and/or corn particles toparticle sizes less than about 7/64 inch or, in another example, lessthan about 10/64 inch and allow for the release of oil therefrom todefine free oil. In one example, the screen size for separating theparticles can range from about 24/64 inch to about 2/64 inch. In anotherexample, the resulting particle sizes are from about 50 microns to about3 mm. The grinding also helps break up the bonds between the fiber,protein, starch, and germ. In one example, screen size or resultingparticle size may have little to no impact on the ability to separatethe sugar from the remaining kernel or similar raw materialcomponent(s). If the carbohydrate source is pre-ground or initially inparticulate form, the optional grind step 402 may be excluded from thesystem and method 400.

Next, the ground corn flour is mixed with backset liquid at slurry tank404 to create a slurry. Optionally, fresh water may be added so as tolimit the amount of backset needed here. An enzyme(s), such as alphaamylase, optionally can be added to the slurry tank 404 or in a slurryblender (not shown) between the optional first grinding step 402 and theslurry tank 404. The slurry may be heated at the slurry tank 404 fromabout 66° C. (150° F.) to about 93° C. (200° F.) for about 10 min toabout 120 min. The stream from the slurry tank 404 contains about 0.5lb/bu free oil, about 1.5 lb/bu germ (particle size ranges from about 50microns to about 3 mm), about 1.8 lb/bu grit (particle size ranges fromabout 50 microns to about 3 mm), which can include starch, and about4.25 lb/bu fiber (particle size ranges from about 50 microns to about 3mm).

The stream from the slurry tank 404 next may be subjected to an optionalsecond grinding/particle size reduction step 406, which may involve useof a disc mill, hammer mill, a pin or impact mill, a roller mill, agrind mill, or the like, to further grind the corn particles to particlesizes less than about 850 microns and allow for additional release ofoil and protein/starch complexes therefrom. In another example, theparticle sizes are from about 300 microns to about 650 mm. The grindingfurther helps continue to break up the bonds between the fiber, protein,and starch and facilitates the release of free oil from germ particles.The stream from the second grinding/particle size reduction step 406contains about 0.1 to about 1.0 lb/bu free oil.

Prior to subjecting the stream from the slurry tank 404 to the optionalsecond grinding/particle size reduction step 406, the slurry may besubjected to an optional liquid/solid separation step 408 to remove adesired amount of liquids therefrom. The liquid/solid separation step408 separates a generally liquefied solution (about 60% to about 80% byvolume), which includes free oil, protein, and fine solids (which do notneed grinding), from heavy solids cake (about 20% to about 40% byvolume), which includes the heavier fiber, grit, and germ, which caninclude bound oil, protein, and/or starch. The liquid/solid separationstep 408 uses dewatering equipment, e.g., a paddle screen, a vibrationscreen, screen decanter centrifuge or conic screen centrifuge, apressure screen, a preconcentrator, a filter press, or the like, toaccomplish separation of the solids from the liquid portion. The finesolids can be no greater than 200 microns. In another example, the finesolids are no greater than 500 microns, which is generally dependentupon the screen size openings used in the liquid/solid separationdevice(s).

In one example, the dewatering equipment is a paddle screen, whichincludes a stationary cylinder screen with a high speed paddle withrake. The number of paddles on the paddle screen can be in the range of1 paddle per 4 to 8 inches of screen diameter. In another example, thedewatering equipment is a preconcentrator, which includes a stationarycylinder screen with a low speed screw conveyor. The conveyor pitch onthe preconcentrator can be about ⅙ to about ½ of the screen diameter.The number of paddles on the paddle screen and the conveyor pitch on thepreconcentrator can be modified depending on the amount of solids in thefeed. The gap between the paddle screen and paddle can range from about0.04 inch to about 0.2 inch. A smaller gap gives a drier cake withhigher capacity and purer fiber but loses more fiber to filtrate. Alarger gap gives a wetter cake with lower capacity and purer liquid(less insoluble solid). The paddle speed can range from 400 to 1200 RPM.In another example, the paddle speed can range from 800 to 900 RPM. Ahigher speed provides higher capacity but consumes more power. Onesuitable type of paddle screen is the FQ-PS32 paddle screen, which isavailable from Fluid-Quip, Inc. of Springfield, Ohio.

The screen for the dewatering equipment can include a wedge wire typewith slot opening, or a round hole, thin plate screen. The round holescreen can help prevent long fine fiber from going through the screenbetter than the wedge wire slot opening, but the round hole capacity islower, so more equipment may be required if using round hole screens.The size of the screen openings can range from about 45 microns to about500 microns. In another example, the screen openings can range from 100to 300 microns. In yet another example, the screen openings can rangefrom 200 to 250 microns. Smaller screen openings tend to increase theprotein/oil/alcohol yield with higher equipment and operation cost,whereas larger screen openings tend to lower protein/oil/alcohol yieldwith less equipment and operation cost.

Returning now to the optional second grinding/particle size reductionstep 406, the wet cake or dewatered solids portion of the stream at theliquid/solid separation step 408 (about 60% to 65% water) next may besubjected to the optional second grinding/particle size reduction step406, as described above. After milling, the solids can be mixed with theliquefied starch solution from the liquid/solid separation step 408, asshown, to form a heavy slurry then subjected to liquefaction step 410.

In particular, the liquefaction step 410 itself can include multiplesteps as discussed above and shown in FIG. 3 . In one embodiment, the pHcan be adjusted here to about 5.2 to about 5.8 and the temperaturemaintained between about 50° C. to about 105° C. so as to convert theinsoluble starch in the slurry to soluble or liquid starch. Other pHranges, such as from pH 3.5 to 7.0, may be utilized and an acidtreatment system using sulfuric acid, for example, may be used as wellfor pH control and for conversion of the starches to sugars. The slurrymay be further subjected to jet cooking whereat the slurry is fed to ajet cooker, heated to about 120° C., held for about 2 min to about 30min, then forwarded to a flash tank. The jet cooker creates a sheeringforce that ruptures the starch granules to aid the enzyme in reactingwith the starch inside the granule and for hydrating the starchmolecules. In another embodiment, the slurry can be subjected to asecondary slurry tank whereat steam is injected directly to thesecondary slurry tank and the slurry is maintained at a temperature fromabout 80° C. to about 100° C. for about 30 minutes to about one hour. Inyet another embodiment, the slurry can be subjected to a secondaryslurry tank with no steam. In particular, the slurry is sent to asecondary slurry tank without any steam injection and maintained at atemperature of about 80° C. to about 90° C. for 1 to 2 hours.Thereafter, the liquefied slurry may be forwarded to a holding tank fora total holding time of about 1 hour to about 4 hours at temperatures ofabout 80° C. to about 90° C. to complete the liquefaction step 410. Withrespect to the optional liquefaction step 410, pH, temperature, and/orholding time may be adjusted as desired.

The slurry stream after the liquefaction step 410 has about 25% to about36% dry solids (DS) content with all the components contained in thecorn kernels, including starches/sugars, protein, fiber, germ, grit,oil, and salts, for example. There generally are three types of solidsin the liquefaction stream: fiber, germ, and grit, which can includestarch and protein, with all three solids having about the same particlesize distribution. The stream from the liquefaction step 410 containsabout 1.0 lb/bu free oil, about 1.5 lb/bu germ particle (size rangesfrom less about 50 microns to about 1 mm), about 4.50 lb/bu protein(size ranges from about 50 microns to about 1 mm), and about 4.25 lb/bufiber (particle size ranges from about 50 microns to about 3 mm).

From the liquefaction step 410, the liquefied sugar stream can be sentto saccharification step 412 whereat complex carbohydrate andoligosaccharides are further broken down into simple sugars,particularly single glucose sugar molecules (i.e., dextrose) to producea liquefied mash. In particular, at the saccharification step 412, theslurry stream may be subjected to an optional two-step cook process. Thefirst part of the cook process, in one example, includes adjusting thepH to about 3.5 to about 7.0, with the temperature being maintainedbetween about 30° C. to about 100° C. for 1 to 6 hours to furtherconvert the insoluble starch in the slurry to soluble starch,particularly dextrose. In another example, the pH can be 5.2 to 5.8 or5.5, for example. In another example, the temperature can be maintainedat 80° C. for about 5 hours. Also, an enzyme, such as alpha-amylase maybe added here. In one example, the amount of alpha-amylase may be fromabout 0.0035 wt % to about 0.04 wt % of the slurry stream. In anotherexample, the amount of alpha-amylase may be from about 0.02 wt % toabout 0.1 wt % of the total stream.

The second part of the cook process, in one example, may includeadjusting the pH to about 3.5 to about 5.0, with the temperature beingmaintained between about 30° C. to about 120° C. for about 10 minutes toabout 5 hours so as to further convert the insoluble starch in theslurry to soluble starch, particularly dextrose. In another example, thepH can be 4.5. In another example, the temperature can be maintainedfrom about 54° C. (130° F.) to 74° C. (165° F.) for about 4 hours or upto about 60 hours. An enzyme, such as glucoamylase, also may be addedhere. In one example, the amount of glucoamylase may be from about 0.01wt % to about 0.2 wt % of the slurry stream. In another example, theamount of glucoamylase may be from about 0.08 wt % to about 0.14 wt % ofthe slurry stream. Other enzymes or similar catalytic conversion agentsmay be added at this step or previous steps that can enhance starchconversion to sugar or yield other benefits, such as fiber or cellulosicsugar release, conversion of proteins to soluble proteins, or therelease of oil from the germ.

A saccharified sugar stream having a density of about 1.05 grams/cc toabout 1.15 grams/cc can result here. At this point, the saccharifiedsugar stream may be no less than about 90 DE. In another example, thesaccharified sugar stream may be no less than 20, 30, 40, 50, 60, 70, or80 DE. In this example, the saccharified In this example, thesaccharified sugar stream can have a total solids fraction of about 25%to about 36%, such solids including sugar, starch, fiber, protein, germ,oil, and ash, for example. In yet another example, the total fermentablecontent of the stream is no more than 20, 30, 40, 50, 60, 70 or 80% ofthe total solids content in the stream. The remaining solids are fiber,protein, oil, and ash, for example. The stream from the saccharificationstep 412 contains about 0.1 lb/bu to about 1.0 lb/bu free oil.

After the saccharification step 412 (but before any fermentation orother processing of the sugar stream), so as to provide a more desirablesugar stream, the saccharified sugar stream can be subjected to asolid/liquid separation step 414 and an oil/saccharified starch solutionseparation step 416. In particular, the solid/liquid separation step 414uses any suitable filtration device, e.g., a pre-concentrator, paddlescreen, pressure screen, fiber centrifuge, decanter, and the like, toseparate the liquid from the solid material. The screen openings canrange from about 50 microns to about 500 microns and will be selected todesirably separate the fiber, grit, and germ particles from the liquid,which primarily includes the saccharified starch solution with smallamounts of oil, free protein (mainly gluten), and starch. In oneexample, the screen openings are about 50 microns.

The liquid portion can go to the oil/saccharified starch solutionseparation step 416 whereat the liquid portion can be subjected to anoil separation device to separate out the oil before sending thesaccharified starch solution to the microfiltration (or similarfiltration) step 418, which is discussed below. The oil/saccharifiedstarch solution separation step 416 can use any type of oil separationdevice, such as a mud centrifuge, two or three phase decanter, discdecanter, two or three phase disc centrifuge, flotation tank, dissolvedair flotation tank/system, and the like, to separate oil from the sugarstream by taking advantage of density differences. With a three-phasedevice, such as a three phase centrifuge or decanter, a heavier solidsportion optionally can be separated out at the oil/saccharified starchsolution step 416 from the oil and saccharified starch solution. Atoil/saccharified starch solution separation step 416, the saccharifiedstarch solution is used as heavy media liquid to float the oil, whichhas a density of about 1.05 grams/cc to about 1.15 grams/cc. The oilthat is recovered at this stage in the process has a much more desirablequality in terms of color and free fatty acid content (from about 2% toabout 5%) as compared to oil that is recovered downstream, particularlyoil recovered after fermentation. In particular, the color of thepre-microfiltration recovered oil is lighter in color and lower in freefatty acid content. The oil yield can include 0.1 lb/bu or greater. Inone example, the oil yield is from about 0.1 lb/bu to about 1.0 lb/bu.

The separated solids portion from the solid/liquid separation step 414can meet up with the solids from the microfiltration (or similarfiltration) step 418 and be subjected to a further biochemicalconversion processing step 420. When the oil/saccharified starchsolution separation step 416 is a three phase separation step, thesolids portion is also sent to the further processing step 420.Optionally, a portion of the solids portion from the oil/saccharifiedstarch solution separation step 416 may be sent to the microfiltrationstep 418. In an embodiment, the further processing step 420 is afermentation step where the sugars are converted, e.g., via a fermenter,to alcohol, such as ethanol or butanol or any other fermentationconversion process or similar sugar utilization/conversion process,followed by distillation and/or separation of the desired component(s)(not shown), which can recover the alcohol or byproduct(s)/compound(s)produced, as is described above with respect to the system and method400. Following distillation or desired separation step(s), the systemand method 400 can include any back end type process(es), which may beknown or unknown in the art to process, for example, the whole stillage.The fermentation step may be part of an alcohol production system thatreceives a sugar stream that is not as desirable or clean, i.e.,“dirtier,” than the sugar stream being sent and subjected to the samefermentation step as the dirty sugar stream. Other options for thesolids stream, aside from fermentation, can include further processingor refining of the solids into feed, microbe based fermentation (asopposed to yeast based) and other various chemical, pharmaceutical ornutraceutical processing (such as propanol, isobutanol, citric acid orsuccinic acid), and the like. Such processing can occur via a reactor,which can include a fermenter.

After the oil/saccharified starch solution separation step 416 (butbefore any potential fermentation or processing of the sugar stream), soas to provide a more desirable sugar stream, the saccharified sugarstream can be subjected to microfiltration step 418, which can include arotary vacuum filter, micro-filter, membrane filtration,precoat/diatomaceous earth filter a belt filter, or the like, to producea more desirable sugar stream, which may be considered a purified orrefined sugar stream, by substantial separation of the solids portion,primarily fiber, germ, grit, which can include protein, from the liquidsugar portion, which primarily includes sugar (e.g., dextrose), residualoil, and fine solids. In one example, the filter screen size here may befrom about 0.1 micron to about 100 microns. In another example, thefilter screen size may be from about 5 microns to about 50 microns. Dueto the input of water, the sugar stream may have a total solids fractionof 20% to 35%. In this example, the sugar stream here may be considereddesirable or “clean” enough, such as for use in biochemical production,because the total insoluble (unfermentable) solids fraction of thestream is less than or equal to 10%. In another example, the totalinsoluble (unfermentable) solids fraction of the stream is less than orequal to 7%. In another example, the total insoluble (unfermentable)solids fraction of the stream is less than or equal to 5%. In anotherexample, the total insoluble (unfermentable) solids fraction of thestream is less than or equal to 3%. In another example, the totalinsoluble (unfermentable) solids fraction of the stream is less than orequal to 1%. In still another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to10%, 15%, 20%, 25%, or 30%.

At this point, the separated sugar stream may be no less than about 90DE. In another example, the separated sugar stream may be no less than20, 30, 40, 50, 60, 70, or 80 DE. In this example, the sugar stream heremay be considered desirable or “clean” enough, such as for use inbiochemical production, because the total insoluble (unfermentable)solids fraction of the stream is less than or equal to 10% of the totalsolids of the stream. In another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to7%. In another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 5%. In another example,the total insoluble (unfermentable) solids fraction of the stream isless than or equal to 3%. In another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to1%. In still another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 10%, 15%, 20%, 25%, or30%. In this example, the stream sent to microfiltration step 418 mayhave a total solids fraction of about 23%, with a range of about 20% toabout 35%, such solids including sugar, starch, fiber, protein, and/orgerm, for example.

The microfiltration step 418 may be replaced by, or additionallyinclude, ultrafiltration, carbon column color removal, filter press,flotation, adsorption, and/or demineralization technologies (e.g., ionexchange). Resin refining, which includes a combination of carbonfiltration and demineralization in one step, can also be utilized forrefining the sugars. Additionally, due to a low solids content of thesugar stream here, an optional evaporation step (not shown) may be addedhereafter to further concentrate the total solids fraction.

As described above, the heavy or solids (raffinate) components from themicrofiltration step 418 can be sent to meet up with the separatedsolids portion from the solid/liquid separation step 414 and theoptional solids portion from the oil/saccharified starch solutionseparation step 416 and subjected to biochemical conversion process step420. These heavier components, or underflow, can be more concentrated intotal solids at about 25% or in a range of about 20% to about 35%.

In one example, prior to the biochemical conversion process step 420,the combined streams may be subjected to an optional thirdgrinding/particle size reduction step 422, which may involve use of adisc mill, hammer mill, a pin or impact mill, a roller mill, a grindmill, or the like for further grinding of particles. Prior to subjectingthe combined streams to the optional third grinding/particle sizereduction step 422, the stream may be subjected to an optionalliquid/solid separation step 424 to remove a desired amount of liquidstherefrom. The liquid/solid separation step 424 separates the liquidportion of the combined stream, which can include remaining free oil,protein, and fine solids (which do not need grinding), from remainingheavy solids cake, which includes the heavier fiber, grit, and germ,which can include bound oil, protein, and/or starch. The liquid/solidseparation step 424 uses dewatering equipment, e.g., a paddle screen, avibration screen, screen decanter centrifuge or conic screen centrifuge,a pressure screen, a preconcentrator, a filter press, or the like, toaccomplish separation of the solids from the liquid portion. The finesolids can be no greater than 200 microns. In another example, the finesolids are no greater than 500 microns, which is generally dependentupon the screen size openings used in the liquid/solid separationdevice(s).

In one example, the dewatering equipment is a paddle screen, whichincludes a stationary cylinder screen with a high speed paddle withrake. The number of paddles on the paddle screen can be in the range of1 paddle per 4 to 8 inches of screen diameter. In another example, thedewatering equipment is a preconcentrator, which includes a stationarycylinder screen with a low speed screw conveyor. The conveyor pitch onthe preconcentrator can be about ⅙ to about ½ of the screen diameter.The number of paddles on the paddle screen and the conveyor pitch on thepreconcentrator can be modified depending on the amount of solids in thefeed. The gap between the paddle screen and paddle can range from about0.04 to about 0.2 inch. A smaller gap gives a drier cake with highercapacity and purer fiber but loses more fiber to filtrate. A larger gapgives a wetter cake with lower capacity and purer liquid (less insolublesolid). The paddle speed can range from 400 to 1200 RPM. In anotherexample, the paddle speed can range from 800 to 900 RPM. A higher speedprovides higher capacity but consumes more power. One suitable type ofpaddle screen is the FQ-PS32 paddle screen, which is available fromFluid-Quip, Inc. of Springfield, Ohio.

The screen for the dewatering equipment can include a wedge wire typewith slot opening, or a round hole, thin plate screen. The round holescreen can help prevent long fine fiber from going through the screenbetter than the wedge wire slot opening, but the round hole capacity islower, so more equipment may be required if using round hole screens.The size of the screen openings can range from about 45 microns to about500 microns. In another example, the screen openings can range from 100to 300 microns. In yet another example, the screen openings can rangefrom 200 to 250 microns.

The wet cake or dewatered solids portion of the stream at theliquid/solid separation step 424 next may be subjected to the optionalthird grinding/particle size reduction step 422, as described above.After milling, the solids can be mixed with the liquid from theliquid/solid separation step 424, as shown, to form a solid/liquidstream then subjected to the biochemical conversion process step 420.

The sugar stream from the microfiltration step 418 can be sent on to afurther processing step, such as a fermentation step where the sugarsare converted, e.g., via a fermenter, to alcohol, such as ethanol orbutanol or any other fermentation conversion process or similar sugarutilization/conversion process, followed by distillation and/orseparation of the desired component(s) (not shown), which can recoverthe alcohol or byproduct(s)/compound(s) produced, as is known in theart. The sugar stream can allow for recovery of a fermentation agentfrom the fermentation step. The fermentation agent can be recovered bymeans known in the art and can be dried as a separate product or, forexample, can be sent to a protein separation step or otherstreams/steps, in the system and method 400, which can allow for captureof the fermentation agent and/or used for further processing.Fermentation agent (such as yeast or bacteria) recycling can occur byuse of a clean sugar source. Following distillation or desiredseparation step(s), the system and method 400 can include any back endtype process(es), which may be known or unknown in the art to process,for example, the whole stillage. The fermentation step may be part of analcohol production system that receives a sugar stream that is not asdesirable or clean, i.e., “dirtier,” than the sugar stream being sentand subjected to the same fermentation step as the dirty sugar stream.Other options for the sugar stream, aside from fermentation, can includefurther processing or refining of the glucose to fructose or othersimple or even complex carbohydrates, processing into feed, microbebased fermentation (as opposed to yeast based) and other variouschemical, pharmaceutical, enzymes, amino acids or nutraceuticalprocessing (such as propanol, isobutanol, citric acid or succinic acid),and the like. Such processing can occur via a reactor, which can includea fermenter. It should be noted that those skilled in the art willunderstand that the microfiltration system can include one or more unitsand may be situated in series and/or parallel flow.

Also, further modifications can be made to the above systems and methods200, 300, 400 to improve co-product recovery, such as oil recovery usingsurfactants and other emulsion-disrupting agents. In one example,emulsion-disrupting agents, such as surfactants, or flocculants may beadded prior to steps in which emulsions are expected to form or after anemulsion forms in the method. For example, emulsions can form duringcentrifugation such that incorporation of surfactants prior to or duringcentrifugation can improve oil separation and recovery. In one example,the syrup stream pre-oil separation can also have emulsion breakers,surfactants, and/or flocculants added to the evaporation system to aidin enhancing the oil yield. This may result in an additional 0.05 to 0.5lb/bu oil yield gain.

While the present invention has been illustrated by a description ofvarious embodiments and while these embodiments have been described inconsiderable detail, it is not the intention of the applicant torestrict or in any way limit the scope of the appended claims to suchdetail. For example, various enzymes (and types thereof) such asamylase, alpha-amylase, glucoamylase, fungal, cellulase, cellobiose,protease, phytase, and the like can be optionally added, for example,before, during, and/or after any number of steps in the systems andmethods 200, 300, 400 including the slurry tank 204, 304, 404 the secondgrinding step 306, 406 the liquefaction step 208, 310, 410 and/or thesaccharification step 214, 316, 412 such as to enhance the separation ofcomponents, such as to help break the bonds between protein, starch, andfiber and/or to help convert starches to sugars and/or help to releasefree oil. In addition, temperature, pH, surfactant, and/or flocculantadjustments may be adjusted, as needed or desired, at the various stepsthroughout the systems and methods 200, 300, 400 including at the slurrytank 204, 304, 404, etc., such as to optimize the use of enzymes orchemistries. Additional advantages and modifications will readily appearto those skilled in the art. Thus, the invention in its broader aspectsis therefore not limited to the specific details, representativeapparatus and method and illustrative example shown and described.Accordingly, departures may be made from such details without departingfrom the spirit or scope of applicant's general inventive concept.

What is claimed is:
 1. A method for producing a sugar stream with frontend oil separation comprising: mixing ground grain particles with aliquid to produce a slurry including starch and free oil; subjecting theslurry to liquefaction to provide a liquefied starch solution includingthe free oil followed by separating the free oil from the liquefiedstarch solution to produce only two streams with one stream includingthe separated free oil and the other stream including the liquifiedstarch solution, wherein the separating of the free oil occurs prior tosaccharification of the starch to yield an oil by product; thereafter,subjecting at least a portion of the liquefied starch solution tosaccharification to convert the starch to simple sugars and produce asaccharified stream including the simple sugars; after saccharificationbut prior to further processing of the simple sugars, initiallyseparating the saccharified stream, via microfiltration, into a firstsolids portion and a first liquid portion including the simple sugars,wherein the first liquid portion is a sugar stream having a dextroseequivalent of at least 20 DE and a total unfermentable solids fractionthat is less than or equal to 30% of a total solids content; andsubjecting the first solids portion to fermentation followed bydistillation thereby producing ethanol and separately subjecting thesugar stream to at least one of carbon filtration, ion exchange, orevaporation followed by a sugar conversion process to produce abiochemical other than ethanol, which remains separate from the ethanolproduced from the first solids portion.
 2. The method of claim 1 furthercomprising, after mixing the ground grain particles with the liquid toproduce the slurry and prior to subjecting the slurry to liquefaction,subjecting the slurry to grinding.
 3. The method of claim 2 furthercomprising, after mixing the grain particles with the liquid to producethe slurry and prior to subjecting the slurry to the grinding,separating the slurry into a solids portion and a liquid portionincluding the starch and free oil, and wherein subjecting the slurry tothe grinding comprises subjecting the solids portion to the grinding toproduce a ground solids portion, and further comprising rejoining theseparated liquid portion from the slurry with the ground solids portionprior to subjecting the slurry to liquefaction.
 4. The method of claim 1wherein the first liquid portion includes the simple sugars andadditional solids, the method further comprising, after separating thesaccharified stream into the first solids portion and the first liquidportion, separating, via a membrane, the first liquid portion into asecond solids portion including the additional solids and a secondliquid portion including the simple sugars, wherein the second liquidportion comprises refined sugar.
 5. The method of claim 4 furthercomprising rejoining the second solids portion with the first solidsportion and subjecting the rejoined solids portion to fermentationfollowed by distillation.
 6. The method of claim 1 wherein the sugarconversion process is fermentation.
 7. The method of claim 1 wherein thesugar conversion process includes a catalytic or chemical reaction. 8.The method of claim 1 wherein the yield of the oil by-product is greaterthan 0.05 lb/bu.
 9. The method of claim 1 wherein separately subjectingthe sugar stream to at least one of carbon filtration, ion exchange, orevaporation comprises subjecting the sugar stream to carbon filtration,followed by ion exchange, followed by evaporation, and then followed bythe sugar conversion process to produce a biochemical other thanethanol.
 10. A method for producing a sugar stream with front end oilseparation comprising: mixing ground grain particles with a liquid toproduce a slurry including starch and free oil; subjecting the slurry toliquefaction to provide a liquefied starch solution including the freeoil followed by separating a solids portion including fiber and germfrom the liquefied starch solution and then separating the free oil fromthe liquefied starch solution to produce only two streams with onestream including the separated free oil and the other stream includingthe liquified starch solution, wherein the separating of the free oiloccurs prior to saccharification of the starch to yield an oil byproduct; thereafter, subjecting at least a portion of the liquefiedstarch solution to saccharification to convert the starch to simplesugars and produce a saccharified stream including the simple sugars;after saccharification but prior to further processing of the simplesugars, initially separating the saccharified stream, viamicrofiltration, into a first solids portion and a first liquid portionincluding the simple sugars, wherein the first liquid portion is a sugarstream having a dextrose equivalent of at least 20 DE and a totalunfermentable solids fraction that is less than or equal to 30% of atotal solids content; and subjecting the first solids portion tofermentation followed by distillation thereby producing ethanol andseparately subjecting the sugar stream to at least one of carbonfiltration, ion exchange, or evaporation followed by a sugar conversionprocess to produce a biochemical other than ethanol, which remainsseparate from the ethanol produced from the first solids portion. 11.The method of claim 10 further comprising, after separating the free oilfrom the liquefied starch solution, rejoining and subjecting theseparated solids portion and the liquefied starch solution tosaccharification.
 12. The method of claim 10 further comprisingcombining the separated solids portion from the liquefied starchsolution and the first solids portion and subjecting the combined solidsportions to fermentation followed by distillation thereby producingethanol.
 13. The method of claim 12 further comprising, after combiningthe separated solids portion from the liquefied starch solution and thefirst solids portion, separating the combined solids portions into athird solids portion and a third liquid portion, subjecting the thirdsolids portion to grinding, and rejoining the separated third liquidportion with the ground third solids portion then subjecting thecombination to fermentation followed by distillation thereby producingethanol.
 14. The method of claim 10 wherein separately subjecting thesugar stream to at least one of carbon filtration, ion exchange, orevaporation comprises separately subjecting the sugar stream to carbonfiltration, followed by ion exchange, followed by evaporation, and thenfollowed by the sugar conversion process to produce a biochemical otherthan ethanol.
 15. A method for producing a sugar stream with front endoil separation comprising: mixing ground grain particles with a liquidto produce a slurry including starch and free oil; subjecting the slurryto liquefaction to provide a liquefied starch solution including thefree oil followed by separating the free oil from the liquefied starchsolution to produce only two streams with one stream including theseparated free oil and the other stream including the liquified starchsolution, wherein the separating of the free oil occurs prior tosaccharification of the starch to yield an oil by product; thereafter,subjecting at least a portion of the liquefied starch solution tosaccharification to convert the starch to simple sugars and produce asaccharified stream including the simple sugars; after saccharificationbut prior to further processing of the simple sugars, initiallyseparating the saccharified stream into a first solids portion and afirst liquid portion including the simple sugars, wherein the firstliquid portion is a sugar stream having a dextrose equivalent of atleast 20 DE and a total unfermentable solids fraction that is less thanor equal to 30% of a total solids content; and subjecting the firstsolids portion to fermentation followed by distillation therebyproducing ethanol and separately subjecting the sugar stream to at leastone of carbon filtration, ion exchange, or evaporation followed by asugar conversion process to produce a biochemical other than ethanol,which remains separate from the ethanol produced from the first solidsportion.
 16. The method of claim 15 wherein after saccharification butprior to further processing of the simple sugars, initially separatingthe saccharified stream, via filtration, into a first solids portion anda first liquid portion including the simple sugars.